A timer is a device or software that counts down from a specified time interval to zero. It is commonly used in cooking, sports, and various activities to help manage time effectively. Timers can be digital or mechanical and often include features like alarms to signal when the time is up. Timers are useful in many settings, such as in classrooms for timed tests or in laboratories for experiments. They can also be found in everyday gadgets like microwaves and smartphones, where they assist users in keeping track of time for various tasks.